Remove a useless checkState call. It serves no purpose since unknown commit.

PiperOrigin-RevId: 316728175
diff --git a/src/main/java/com/google/devtools/build/lib/packages/GlobCache.java b/src/main/java/com/google/devtools/build/lib/packages/GlobCache.java
index cb2d512..a90252c 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/GlobCache.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/GlobCache.java
@@ -254,7 +254,6 @@
     }
 
     HashSet<String> results = new HashSet<>();
-    Preconditions.checkState(!results.contains(null), "glob returned null");
     for (String pattern : includes) {
       List<String> items = getGlobUnsorted(pattern, excludeDirs);
       if (!allowEmpty && items.isEmpty()) {